AS3955 datasheet(44/102 Pages) AMSCO

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[v1-04] 2016-Feb-03

AS3955 − Detailed Description

Configuration Bytes MIRQ_0 and MIRQ_1

These two bytes define the default value of the volatile memory

for Mask Interrupt Register 0 and Mask Interrupt Register 1

registers. These bytes can always be accessed for read and write

via the SPI / I²C and can be accessed for read and write from the

RF side if rfcfg_en is set to 1.

AS3955 Communication Modes

AS3955 supports three different modes. The basic

communication mode is a standalone mode where AS3955 can

behave as a standalone NFC tag without MCU intervention. The

other two modes (Tunneling and Extended mode) represent

modification of the communication in SELECTED state. The

anti-collision process is the same for all three modes.

It is possible to change the mode of operation at any time.

In case Tunneling and Extended mode are both enabled,

Tunneling mode has priority over Extended mode.

Standalone NFC Type 2 Tag Mode

If neither of the two modes are enabled (Tunneling and

Extended mode) in IC Configuration Register 2, the tag is in

standalone mode. In this mode, all RF incoming commands

address the internal EEPROM. In this mode, it is always possible

to connect the MCU since all other functionalities of AS3955 are

not limited by the communication modes. The main purpose of

this mode is to use the AS3955 as a standalone chip or a chip

in combination with MCU where the MCU is used for managing

AS3955 configuration and memory content.

Tunneling Mode

Tunneling mode enables transparent data transfer between

NFC device and MCU. In this mode, the internal EEPROM cannot

be accessed via RF and any type of data received will be

forwarded to MCU when the tag is in SELECTED state. An error

during the reception will trigger a corresponding interrupt. In

this mode the MCU shall take care for the correct response. For

this purpose, the MCU may issue an ACK or a different type NAK

response using implemented commands.

By enabling this mode, the MCU can emulate NFC type 2 tags,

NFC type 4 tags, ISO14443A Level 3 cards, ISO14443A Level 4

cards, and also implement higher level protocols such as

[PHDC].

Tunneling mode can be configured by setting Configuration

Byte IC_CFG2 in EEPROM or the corresponding register

( IC Configuration Register 2).

This mode also allows access to the internal EEPROM via the SPI

/ I²C during RF communication.

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